Glass Room Extension Cost

Want to know how much it costs to install a glass room extension?

Every aspect of a glass extension will impact the price, including size, custom features, materials, and the glass. In this guide, we’ll cover everything you need to know about glass extensions and how much they cost.

A glass extension differs from project to project. Some may have sliding doors, others may have retractable roofs, and others may be entirely unique and bespoke.

With MyJobQuote, you can request several glass box extension quotes from local glass extension builders. It's fast, free, and there's no obligation to go ahead!

How Much Does a Glass Room Extension Cost?

Glass room extension costs average around £3,000 per m², with a typical 14m² extension costing approximately £40,000. Glass extension costs typically include the glass panels, frames, and installation.

Before we offer specific price ranges, it is important to note what is included within glass extension costs. The majority of projects will include the glass panels, the frames, and the installation. A huge selling point of a glass extension is that, unlike other traditional home extensions, a glass extension requires much simpler foundations and, as such, the project tends to be much quicker to complete.

The complexity of the project will impact glass extension costs, so any bespoke features must be considered. There is also price variation between full glass room extensions and smaller side return glass extensions.

Below, we have laid out the key prices in a helpful table.

Glass Room Extension Prices

Supply Costs for Glass Room Extensions

Glass room extension supply costs account for a good portion of the overall project budget. You will need glass and frames, typically made from aluminium for structural stability and sleekness.

Glass panels cost £200 to £500 per m², although for larger designs the total material cost can be as much as £3,000 per m² for high-performance glazing systems. People usually opt for double-glazing for thermal efficiency, though single glazing is less expensive.

Frame costs vary by material:

• Aluminium framing (per m²): £50 - £150
• Steel framing (per m²): £100 - £300
• uPVC framing (per m²): £40 - £100

Bespoke options require extremely high quality glass and therefore increase costs significantly.

Additional Costs

Structural Work and Reinforcement

The beauty of glass room extensions is that they do not require the same level of foundations as other extension designs. However, they will still need structural reinforcements on your existing home to ensure that the glass room is stable and sound. Now, this is typically included in the overall price, but if extensive work is required on your existing home, this would raise the price of your glass extension project.

You can find more prices here for projects related to the preparation for extensions.

Heating and Cooling Systems

While glass may not offer the same natural thermal insulation as other materials, advances like double glazing, high-quality glass, and modern triple-glazed units can enhance comfort and help maintain a pleasant environment year-round, making a glass extension enjoyable in most seasons.

In winter, underfloor heating and installing central heating will be crucial for keeping a glass extension comfortable enough to spend time in. Similarly, in the summer, you may find that the glass amplifies the temperature, so installing air conditioning and fans can make it manageable.

Blinds and shading are also cost-effective ways to keep heat out of your glass extension during the warm months.

Plumbers and Electricians

Depending on how you are planning to use your glass extension, you may need to consider plumber prices with a day rate of around £130 to £200 (although this can rise to £500 in areas such as London).

Meanwhile, for jobs such as installing plug sockets and wiring, electricians in the UK charge around £250 to £375 (again with higher prices within the capital).

Architectural and Design Fees

When planning a glass extension, asking for help from a professional designer or architect can play a vital role in the final appearance. Especially if you're aiming for a bespoke finish or need to adapt the glass extension structure to suit your existing property layout.

Architectural design may need to be taken into consideration, even for a straightforward glass extension build. However, they are particularly important for a bespoke project or unique renovation and if required, can cost between £1,000 and £3,000.

Other potential fees related to planning permission and building regulation are covered separately.

Labour Costs and Timescales for Glass Room Extensions

The cost of labour must be considered when planning a glass extension, and while it will be included in the final quote you receive, it can be helpful to see how this is worked out.

Most glass extension specialists provide fixed total project quotes based on area and complexity, though supporting trades typically charge hourly rates for electrical and plumbing work.

The table below breaks down labour costs and timescales by project phase:

Cost Factors for Glass Room Extensions

Glass Type and Quality

As glass is the main component in a glass extension, the different types of glass you have as an option impact the price quite greatly. Simple single-glazing glass can be obtained for as little as £200 per m², but it will offer little thermal performance and may be more susceptible to damage. Double and triple glazing is much more appropriate for a glass extension, costing between £300-£450 per m², and even higher quality triple glazing glass with UV protection tops the range at around £500 per m².

Location and Property Type

The type of property you live in can impact the price, mainly based on access and size. If you have a semi-detached home, you probably won't have a space as large as that of a full detached, but this really depends on a project-by-project basis and, of course, how big you want your glass extension to be. On another note, the price of materials and labour differs from region to region, so you may see that highlighted as you begin to attain quotes.

Custom Features

Any custom or bespoke features will drive the price of your project up. Complex glass extension installations take more time and effort, but there will also be a lot more time spent on the planning and design stage. Architectural designs, sliding doors, and impressive additionals like motorised blinds will all be incredibly effective but costly, so factor this into your budget.

Types of Glass Room Extensions

Frameless Glass Box Extension

A frameless glass box extension is made primarily of glass panels without much visible structural framing. Essentially, it provides an unobstructed, clear view, letting in ample natural light and creating an open, modern aesthetic. These are the types of glass room that will cost around £40,000 and are most commonly installed.

Pros:

• ✔ Lots of natural light
• ✔ Sleek, high-end design
• ✔ Makes great use of outdoor areas

Cons:

• ✖ Lack many features
• ✖ Can be costly to maintain temperate in extreme weather months

Conservatory Style

This glass room style is designed to look more like a traditional extension with very clear, visible framing. It is still made up predominantly of glass, so you still get all of the light and extra living space effects, but it is somewhat subdued in comparison to the frameless. These may be a little less than £40,000 due to the more visible framing.

Pros:

• ✔ Some natural light
• ✔ Cost-effective
• ✔ Makes great use of outdoor areas

Cons:

• ✖ Lack many features
• ✖ It can be costly to maintain temperature in extreme weather months
• ✖ Visible frames are not always the desired aesthetic

Retractable Roof Extensions

This option is similar to frameless but with the added feature of a retractable roof for open air. Not only is this very comfortable to use in the summer months, but it allows the maximum possible light and living space effects. This will be on the more expensive end of the range, costing around £55,000.

Pros:

• ✔ Lots of light
• ✔ Makes great use of outdoor areas

Cons:

• ✖ Can be costly to install
• ✖ It can be costly to maintain temperature in extreme weather months

Alternative Types of Extensions

Traditional Conservatories

Conservatories (such as a lean to conservatory) are usually a cheaper option than a glass extension to erect, and they offer more insulation, making it easier to maintain interior temperatures. They typically feature glass panels with uPVC framing, but can look old-fashioned and don’t always have the same indoor-outdoor connection as glass extensions.

Sunrooms

Sunrooms are somewhat in between glass rooms and conservatories. Sun room extension costs are typically cheaper than glass rooms and offer more natural light and space than conservatories, but they are still not at the same level as glass rooms. They are built with a combination of brickwork walls, glass and frames and can be considered a hybrid of the two.

Orangeries

Orangeries are generally extensions of the home entirely, usually with standard bricked exterior walls but with large glass roofing for a more solid, structured look. They offer plenty of natural light but without offering the feeling of bringing the outdoors in.

Building Regulations Related to Glass Room Extensions

Building regulations are in place to ensure that any new glass extension in the UK is safe, energy-efficient, and structurally sound. Now, these regulations apply to most types of extensions and are not limited to glass rooms, covering areas such as structural integrity, fire safety and thermal efficiency. Here are the main building regulations related to glass room extensions:

Thermal Efficiency

Glass rooms often involve extensive glazing, so they need to meet insulation requirements to prevent excessive heat loss. Building regulations require that walls, floors, roofs, and windows are thermally efficient, so, for instance, the U-values of the glass should meet minimum standards to retain heat during colder months and reduce overheating in summer.

Using double or triple glazing is often necessary to meet these standards, and your contractor will be able to provide guidance on how to achieve these regulations.

Structural Integrity

Here we need to ensure that the structural stability of the glass room can support the weight of the glass panels. Your contractor must verify that the supporting walls, beams, and other structural elements can safely bear the load. If your glass room has a retractable or sliding roof, it will also need to be designed to withstand local wind levels.

Fire Safety

Glass rooms must have appropriate fire-resistant materials and follow escape route guidelines if they are part of the main home. In addition, certain fire safety standards apply to buildings close to boundaries or neighbouring properties. For instance, the structure may need to include fire-resistant walls or partitions, especially if close to property lines. Again, this will be reviewed by your contractor and advice provided.

Planning Permission

Glass extensions usually fall under the permitted development rights, meaning you don’t normally require planning permission. Just as long as the new glass extension meets size and placement rules.

However, the exemption is if your property is a listed building, in a conservation area or already protected for another reasons. In which case, you’ll need to apply for planning permission through your Local Planning Authority (LPA).

Hiring Contractors Checklist for Glass Extensions

Hiring a professional is one of the most important steps in any glass extension project, and it’s worth dedicating time and thought to the process. Here are some top tips for finding and hiring the right professional.

• Compare Multiple Quotes: Never settle for the first quote you receive; instead, reach out to several professionals in your area for estimates. This not only helps ensure you’re getting a fair price, but different experts may also suggest unique ideas for your project that you hadn’t considered. For a glass box extension, there are many benefits to speaking to many contractors and collecting opinions on the possibilities for your space.
• Check Reviews and Testimonials: There are so many online resources like MyJobQuote that it’s never been easier to see how others rate a tradesperson's work. Reviews and examples of past projects will give you a lot of insight into the quality of glass extension builders and the work they have done.
• Word of Mouth: Personal recommendations are still invaluable. Ask around, especially if you know of someone in your area who’s had an extension completed recently.

Removing Existing Structures Before Installing a Glass Room Extension

We mentioned earlier that the preparation work prior to the erecting of your glass box extension is crucial. A good base for your new glass box extension will ensure everything from weatherproofing to levelling is completed and will stand you in good stead for the rest of your glass extension project. This initial preparation will cost in the region of £50-£150 per m², and it will be money well spent.

If there are any existing structures, this will need to be removed first. This is generally undertaken by a labourer at a rate of around £150 per day, and you should ensure that this has been factored into your glass extension quote.

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